NXP Semiconductors MIMXRT685SFAWBR

Overview

MIMXRT685SFAWBR from NXP Semiconductors is a dual-core Arm Cortex-M33 + Cadence Xtensa HiFi4 Audio DSP microcontroller in WLCSP114 package, operating at up to 300 MHz (M33) and 600 MHz (HiFi4), with 4.5 MB shared SRAM and hardware TrustZone security. It targets ultra-compact voice-enabled edge devices requiring low-power audio processing and secure real-time control.

For engineers reviewing the MIMXRT685SFAWBR datasheet, MIMXRT685SFAWBR pinout, MIMXRT685SFAWBR application, or MIMXRT685SFAWBR equivalent, this page delivers verified core architecture, validated WLCSP114 pin mapping, confirmed peripheral availability (7 Flexcomm interfaces, no eSPI/HS SPI/PMIC I2C), and precise alternative selection guidance for voice and audio SoC designs.

Technical Context

The MIMXRT685SFAWBR integrates two independent execution domains: the Cortex-M33 handles real-time system control, secure boot, and peripheral management using TrustZone-isolated memory regions and Casper crypto coprocessor, while the HiFi4 DSP executes audio codecs and voice pre/post-processing with four 32×32-bit MACs and IEEE single-precision floating-point unit. Both cores share 4.5 MB of partitioned SRAM via arbitration-controlled AHB and dedicated 256-bit DSP interface.

Its clocking architecture includes main PLL, audio PLL, and independent fractional dividers enabling concurrent CPU/DSP operation at different frequencies; power management supports deep-sleep mode with 32 kHz RTC oscillator driving USARTs, and per-SRAM-partition retention control. The WLCSP114 variant omits eSPI, FlexSPI B, HS SPI (Flexcomm 14), and PMIC I2C (Flexcomm 15), limiting interface count but retaining full dual-core functionality and 65 GPIOs.

Key Specifications

Pinout & Package

Package: WLCSP114 (4.235 × 4.235 × 0.525 mm, SOT2019), ball pitch 0.35 mm, 114 I/O balls. Supports triple I/O voltage domains (VDDIOA/B/C) for mixed-voltage interfacing.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar dual-core audio microcontroller applications.

Compared with MIMXRT685SFAWBR, the SFVKB offers expanded interface options in a larger package ideal for development platforms, while the SFFOB sacrifices DSP and security for lower BOM cost - neither matches the WLCSP114's combination of ultra-small size, full dual-core audio capability, and hardware security.

Availability

MIMXRT685SFAWBR is available at Aetrix Electronics and suitable for smart earbuds, voice remote controls, portable voice assistants, and industrial voice interface modules requiring stable component supply and long-term production continuity.

Supply support for MIMXRT685SFAWBR includes scheduled delivery planning, volume procurement assistance, BOM continuity management, traceable sourcing, and lifecycle availability coordination for OEM customers, industrial embedded developers, connected-device designers, and electronics production programs.

Manufacturer

NXP Semiconductors is a global semiconductor leader specializing in secure connectivity solutions for automotive, industrial, and IoT markets, with over 40 years of microcontroller innovation.

The RT600 family, including MIMXRT685SFAWBR, was designed specifically for resource-constrained, battery-powered voice and audio endpoints - integrating high-efficiency DSP, hardware security, and ultra-compact packaging to enable next-generation intelligent edge devices.

FAQ

What is the maximum operating frequency of each core in the MIMXRT685SFAWBR?

The MIMXRT685SFAWBR features an Arm Cortex-M33 core rated for up to 300 MHz and a Cadence Xtensa HiFi4 Audio DSP core rated for up to 600 MHz. These frequencies are achievable under specified 1.8 V ±5% supply and −20 °C to +85 °C ambient conditions. The MIMXRT685SFAWBR datasheet confirms both cores operate concurrently at these speeds with independent clock domains managed by the on-chip PLL system.

Does the MIMXRT685SFAWBR support USB ISP (In-System Programming)?

No, the MIMXRT685SFAWBR does not support USB ISP mode. As documented in Table 2 of the RT600 datasheet, the WLCSP114 package lacks the VBUS pin required for USB enumeration and bootloader detection. To implement USB-based firmware updates, users must route a GPIO to the USB connector's VBUS line and manually trigger the ISP handler via software configuration of the DEVCMDSTAT register.

How many Flexcomm interfaces does the MIMXRT685SFAWBR include, and what protocols do they support?

The MIMXRT685SFAWBR includes seven Flexcomm interfaces (Flexcomm 0 through 7). Each supports UART, I2C, SPI, or I2S protocols via software configuration, with dedicated fractional baud rate generators and integrated FIFOs. Notably, Flexcomm 6 on the WLCSP114 package is restricted to UART, I2C, or I2S only - SPI master mode is not available on that instance, per datasheet footnote [5].

What security features are implemented in the MIMXRT685SFAWBR?

The MIMXRT685SFAWBR implements Arm TrustZone for hardware-enforced memory isolation, AES256 encryption with on-the-fly decryption for FlexSPI, SHA1/SHA2 hash engines, Physical Unclonable Function (PUF) for key generation, 16 Kb OTP for secure storage, and Casper cryptography coprocessor. These features collectively enable secure boot, runtime attestation, and encrypted firmware storage - all confirmed in the RT600 product data sheet sections 2.2 and 4.1.

Is the MIMXRT685SFAWBR pin-compatible with other RT600 family members like MIMXRT685SFVKB?

No, the MIMXRT685SFAWBR is not pin-compatible with MIMXRT685SFVKB or MIMXRT685SFFOB. It uses the WLCSP114 package (114-ball, 0.35 mm pitch), whereas SFVKB uses VFBGA176 (176-ball, 0.65 mm pitch) and SFFOB uses FOWLP249 (249-ball, 0.4 mm pitch). Pin functions and ball assignments differ across packages; migration requires PCB redesign and IOCON register reconfiguration.